Fabrication and hermeticity testing of a glass-silicon package formed using localized aluminum/silicon-to-glass bonding

A hermetic package based on localized aluminum/silicon-to-glass bonding has been successfully demonstrated. Less than 0.2 MPa contact pressure with 46 mA current input for two parallel 3.5 m wide polysilicon microheaters can achieve a strong and reliable bond in 7 minutes. Accelerated testing in an autoclave shows some packages survive more than 200 hours at 3 atm, 100%RH and 128/spl deg/C. Premature failure has been attributed to some unbonded regions on the failed samples. The bonding yield and reliability has been improved by increasing bonding time and applied pressure. Devices using this process have lasted for more than 320 hours under accelerated conditions. The packaging technology is being applied to vacuum encapsulation of resonant devices.